1. Field of the Invention
This invention relates to a very low cost manually operated, trigger actuated liquid dispenser featuring a bellows-type pump having multiple flexible wall sections, pleats or corrugations and molded of inexpensive and readily available plastic materials that are inert to the liquid product to be dispensed.
2. Description of the Prior Art
Manually operated, trigger actuated dispensing pumps for liquid dispensers have been proposed in the past. A particular one that has received wide commercial acceptance is disclosed in U.S. Pat. No. 3,061,202, granted Oct. 30, 1962 to Tracy B. Tyler. This type of pump, however, in general, is complex having many parts and is relatively costly to manufacture, inspect and/or assemble. In addition, some of the individual parts are also complex and costly to manufacture, inspect and/or assemble.
Other prior patents have been granted that are directed toward overcoming the problem of costly manufacture inherent in the structure disclosed in the above-mentioned U.S. Pat. No. 3,061,202, a particular one being U.S. Pat. No. 3,749,290, granted on July 31, 1973 to Lewis A. Micallef. This patent discloses a trigger sprayer having a deformable, tubular member that defines a pump chamber and is designed to be compressively stressed, and collapsed, on a bulbous sidewall by a trigger mechanism to reduce the pump chamber volume and discharge liquid drawn therein from a container. While this pump embodies but few parts and the manufacturing cost of a dispenser embodying such a pump would be expected to be low, the tubular member, as a practical matter, is so expensive to manufacture as to make the manufacturing cost of a dispenser utilizing such a tubular member prohibitively high in the very competitive market in which such dispensers are sold. Specifically, it has been found that special and hard to obtain materials are required to provide the elastic properties necessary for repetitive collapsing of the bulbous sidewalls upon successive depressions and the return each time when released, to the normal molded condition, while meeting at the same time, the insolubility requirements for the liquid product to be dispensed.